Novel approach of controllable stoichiometric fabrication of alloyed Au/Ag nanoparticles by nanosecond laser ablation of thin bi-layered films in water

Abstract

A novel approach was proposed and demonstrated to fabricate in a controllable manner alloyed colloidal Ag/Au nanoparticles with predetermined stoichiometry from thin, magnetrondeposited bilayered (Ag/Au) films of variable layer thickness by their nanosecond laser ablation in water. The optical properties of the obtained colloidal solutions were systematically analyzed, both experimentally and theoretically, indicating the alloyed character of the bimetallic nanoparticles as a monotonic 'red' spectral displacement of the localized plasmon resonance position, as well as gradual variation of its amplitude and width with increasing gold content in the bilayered films. Transmission electron microscopy and energy dispersive xray spectroscopy support the alloyed rather than fragmentary character of the bimetallic nanoparticles, with the increasing gold content resulting in an increasing average nanoparticle size. This approach appears to be highly promising for the controllable ondemand fabrication of different bi and polymetallic nanoparticles with predetermined stoichiometries.

Selective Aerobic Oxidation of 5‐(Hydroxymethyl)furfural over Heterogeneous Silver‐Gold Nanoparticle Catalysts

“…From UV-Vis spectra of the resulting colloidal suspensions, shown in Figure 2b, single absorbance peaks that are shifted linearly with the composition of the particles can be observed (Figure 2c), indicating successful alloy formation. [36] Although the optical properties of the nanoparticles also depend on their size and shape, [37] the respective shifts are in line with literature where comparable particle sizes and shapes were investigated. [38] Slight differences arise from the presence of stabilizing ligands during biological or chemical syntheses, [39] whereas laser-generated alloy nanoparticles give the lowest surface plasmon resonance (SPR) wavelengths due to the absence of such agents.…”

Limited Elemental Mixing in Nanoparticles Generated by Ultrashort Pulse Laser Ablation of AgCu Bilayer Thin Films in a Liquid Environment: Atomistic Modeling and Experiments

“…For ablation conducted with nanosecond pulses, the timescale of the plasma plume formation overlaps with the pulse duration, leading to further heating of the plume, increase in the plasma temperature, and prolongation of the plasma lifetime. , Under these conditions, better elemental mixing can be expected prior to the particle formation, and predominantly bimetallic particles are obtained, even though they can differentiate into biphasic or core–shell morphologies in correlation with nominal nanoparticle composition . This expectation has been experimentally confirmed for bulk binary alloy targets, , as well as for FeAu and AgAu thin films. The effect of the pulse duration on the nanoparticle formation from thin-film targets with an overall composition of Fe 50 Au 50 was recently examined in ref , where a higher abundance of bimetallic FeAu core–shell nanoparticles (>90% by mass) was observed in the case the bilayer targets ablated by nanosecond pulses.…”

“…Recently, the design of target materials for the PLAL synthesis of alloy nanoparticles has been the focus of attention, going from commonly used alloy targets either toward pressed mixed powder targets to improve synthesis variability ,, or toward thin films and multilayer targets. ,, The use of thin films and multilayers adds an additional degree of freedom to the experimental setup and enables more precise control over the laser energy deposition and atomic mixing that defines the composition of the nanoparticles. In particular, the thin-layer PLAL makes it possible to ensure that a well-defined target depth, set by the layer thickness, is ablated in a single-pulse experiment.…”

“…To check the possible implications of this effect on the nanoparticle generation in PLAL, in the present study, we perform simulations and experiments for both Cu-top and Ag-top bilayer targets. In contrast to the earlier experimental studies of nanosecond PLAL of bilayer targets, ,, we utilize ultrashort laser pulses and focus our attention on the degree of compositional uniformity that can be achieved by the laser ablation in liquids. The analysis of the nanoparticle size and composition distributions, as well as the correlation between the size and composition, is performed in both simulations and experiments.…”

Formation of gold/silver composite nanoparticles by pulsed laser ablation of gold–silver layered films in liquid

“…To prepare metal alloy NPs bulk alloys or metal powder mixtures are most commonly applied as targets [45,46]. At the same time, thin metal films either as homogeneous metal alloy films or as segregated metal bilayers/multilayers are less frequently used [47][48][49], although they might be significant. Nikov et al successfully produced gold-silver nanoparticles by PLAL of bimetallic thin films [50], and established a linear dependence of the surface plasmon resonance (SPR) maximum of the colloidal NPs on the metal concentration of the films.…”